Android 自定義實現switch開關按鈕
阿新 • • 發佈：2019-01-08
前幾天在看蘑菇街上有個開關按鈕：
就在想是怎樣實現的，於是反編譯了它的原始碼，但是這時得到了下面的幾張圖片：
圖片對應的名稱：
無色長條:switch_frame;
白色圓點:switch_btn_pressed;
左白右紅的長條:switch_bottom;
黑色長條:switch_mask.
那我們就用這幾張圖片來實現類似的效果吧。
程式碼：
SwitchButton類：
package com.example.switchbutton; import android.content.Context; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.graphics.Canvas; import android.graphics.Paint; import android.graphics.PorterDuff.Mode; import android.graphics.PorterDuffXfermode; import android.graphics.Rect; import android.graphics.RectF; import android.util.AttributeSet; import android.view.MotionEvent; import android.view.View; public class SwitchButton extends View implements android.view.View.OnClickListener{ private Bitmap mSwitchBottom, mSwitchThumb, mSwitchFrame, mSwitchMask; private float mCurrentX = 0; private boolean mSwitchOn = true;//開關預設是開著的 private int mMoveLength;//最大移動距離 private float mLastX = 0;//第一次按下的有效區域 private Rect mDest = null;//繪製的目標區域大小 private Rect mSrc = null;//擷取源圖片的大小 private int mDeltX = 0;//移動的偏移量 private Paint mPaint = null; private OnChangeListener mListener = null; private boolean mFlag = false; public SwitchButton(Context context) { this(context, null); // TODO Auto-generated constructor stub } public SwitchButton(Context context, AttributeSet attrs) { this(context, attrs, 0); // TODO Auto-generated constructor stub } public SwitchButton(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); // TODO Auto-generated constructor stub init(); } /** * 初始化相關資源 */ public void init() { mSwitchBottom = BitmapFactory.decodeResource(getResources(), R.drawable.switch_bottom); mSwitchThumb = BitmapFactory.decodeResource(getResources(), R.drawable.switch_btn_pressed); mSwitchFrame = BitmapFactory.decodeResource(getResources(), R.drawable.switch_frame); mSwitchMask = BitmapFactory.decodeResource(getResources(), R.drawable.switch_mask); setOnClickListener(this); setOnTouchListener(new OnTouchListener() { @Override public boolean onTouch(View v, MotionEvent event) { // TODO Auto-generated method stub return false; } }); mMoveLength = mSwitchBottom.getWidth() - mSwitchFrame.getWidth(); mDest = new Rect(0, 0, mSwitchFrame.getWidth(), mSwitchFrame.getHeight()); mSrc = new Rect(); mPaint = new Paint(); mPaint.setAntiAlias(true); mPaint.setAlpha(255); mPaint.setXfermode(new PorterDuffXfermode(Mode.DST_IN)); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { // TODO Auto-generated method stub setMeasuredDimension(mSwitchFrame.getWidth(), mSwitchFrame.getHeight()); } @Override protected void onDraw(Canvas canvas) { // TODO Auto-generated method stub super.onDraw(canvas); if (mDeltX > 0 || mDeltX == 0 && mSwitchOn) { if(mSrc != null) { mSrc.set(mMoveLength - mDeltX, 0, mSwitchBottom.getWidth() - mDeltX, mSwitchFrame.getHeight()); } } else if(mDeltX < 0 || mDeltX == 0 && !mSwitchOn){ if(mSrc != null) { mSrc.set(-mDeltX, 0, mSwitchFrame.getWidth() - mDeltX, mSwitchFrame.getHeight()); } }
<span style="white-space:pre"> </span>//這兒是離屏緩衝，自己感覺類似雙緩衝機制吧 int count = canvas.saveLayer(new RectF(mDest), null, Canvas.MATRIX_SAVE_FLAG | Canvas.CLIP_SAVE_FLAG | Canvas.HAS_ALPHA_LAYER_SAVE_FLAG | Canvas.FULL_COLOR_LAYER_SAVE_FLAG | Canvas.CLIP_TO_LAYER_SAVE_FLAG); canvas.drawBitmap(mSwitchBottom, mSrc, mDest, null); canvas.drawBitmap(mSwitchThumb, mSrc, mDest, null); canvas.drawBitmap(mSwitchFrame, 0, 0, null); canvas.drawBitmap(mSwitchMask, 0, 0, mPaint); canvas.restoreToCount(count); } @Override public boolean onTouchEvent(MotionEvent event) { // TODO Auto-generated method stub switch (event.getAction()) { case MotionEvent.ACTION_DOWN: mLastX = event.getX(); break; case MotionEvent.ACTION_MOVE: mCurrentX = event.getX(); mDeltX = (int) (mCurrentX - mLastX); // 如果開關開著向左滑動，或者開關關著向右滑動（這時候是不需要處理的） if ((mSwitchOn && mDeltX < 0) || (!mSwitchOn && mDeltX > 0)) { mFlag = true; mDeltX = 0; } if (Math.abs(mDeltX) > mMoveLength) { mDeltX = mDeltX > 0 ? mMoveLength : - mMoveLength; } invalidate(); return true; case MotionEvent.ACTION_UP: if (Math.abs(mDeltX) > 0 && Math.abs(mDeltX) < mMoveLength / 2) { mDeltX = 0; invalidate(); return true; } else if (Math.abs(mDeltX) > mMoveLength / 2 && Math.abs(mDeltX) <= mMoveLength) { mDeltX = mDeltX > 0 ? mMoveLength : -mMoveLength; mSwitchOn = !mSwitchOn; if(mListener != null) { mListener.onChange(this, mSwitchOn); } invalidate(); mDeltX = 0; return true; } else if(mDeltX == 0 && mFlag) { //這時候得到的是不需要進行處理的，因為已經move過了 mDeltX = 0; mFlag = false; return true; } return super.onTouchEvent(event); default: break; } invalidate(); return super.onTouchEvent(event); } public void setOnChangeListener(OnChangeListener listener) { mListener = listener; } public interface OnChangeListener { public void onChange(SwitchButton sb, boolean state); } @Override public void onClick(View v) { // TODO Auto-generated method stub mDeltX = mSwitchOn ? mMoveLength : -mMoveLength; mSwitchOn = !mSwitchOn; if(mListener != null) { mListener.onChange(this, mSwitchOn); } invalidate(); mDeltX = 0; } }
MainActivity：
package com.example.switchbutton; import com.example.switchbutton.SwitchButton.OnChangeListener; import android.app.Activity; import android.os.Bundle; import android.util.Log; import android.view.Menu; import android.widget.Toast; public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); SwitchButton sb = (SwitchButton) findViewById(R.id.wiperSwitch1); sb.setOnChangeListener(new OnChangeListener() { @Override public void onChange(SwitchButton sb, boolean state) { // TODO Auto-generated method stub Log.d("switchButton", state ? "開":"關"); Toast.makeText(MainActivity.this, state ? "開":"關", Toast.LENGTH_SHORT).show(); } }); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.main, menu); return true; } }
activity_main.xml:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin" >
<ImageView
android:id="@+id/imageView"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<com.example.switchbutton.SwitchButton
android:id="@+id/wiperSwitch1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="100dip" />
</LinearLayout>